Why am I being told that I do not qualify for the American Opportunity Credit? I was a full time student, no drug convictions, did not finish a degree prior to 2021

Generally, you can claim the American opportunity credit if all three of the following requirements are met. 

• You pay qualified education expenses of higher education.
• You pay the education expenses for an eligible student.
• The eligible student is either yourself, your spouse, or a dependent you claim on your tax return. 

For more details, refer to chapter 2 on pages 9-22 of the IRS Publication 970

There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working*. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants.  It is usually best if the parent claims that credit. 

You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.

If you are eligible, you have answered  something wrong, in the interview. But, a lot of people are just not eligible. See https://www.irs.gov/Individuals/AOTC

*Reference: Line 7 instructions for form 8863. https://www.irs.gov/instructions/i8863